Summaries for Methylmalonic Aciduria and Homocystinuria, Cbld Type

OMIM
:53
Combined methylmalonic aciduria (MMA) and homocystinuria is a genetically heterogeneous disorder of cobalamin (cbl; vitamin B12) metabolism. The defect causes decreased levels of the coenzymes adenosylcobalamin (AdoCbl) and methylcobalamin (MeCbl), which results in decreased activity of the respective enzymes methylmalonyl-CoA mutase (MUT; 609058) and methyltetrahydrofolate:homocysteine methyltransferase, also known as methionine synthase (MTR; 156570). Different forms of the disorder have been classified according to complementation groups of cells in vitro: cblC (MAHCC; 277400), cblD, cblF (MAHCF; 277380), and cblJ (MAHCJ; 614857).
Isolated methylmalonic acidurias have also been classified by complementation groups: MMA 'mut' (251000), caused by mutation in the MUT gene on chromosome 6p21; MMA cblA (251100), caused by mutation in the MMAA gene (607481) on 4q31; and MMA cblB (251110), caused by mutation in the MMAB gene (607568) on 12q24. Another form of isolated MMA (613646) can be caused by defect in the transcobalamin receptor (CD320; 606475). (277410)

NIH Rare Diseases
:49
Methylmalonic acidemia with homocystinuria, type cblD is an inherited condition in which the body is unable to metabolize certain proteins and fats properly. Signs and symptoms generally develop in the first few months of life and may include failure to thrive, lethargy, vomiting, dehydration, hypotonia, developmental delay, seizures, ataxia (problems with muscle control), feeding difficulties, and an enlarged liver (hepatomegaly). Intellectual disability is a long-term consequence. Methylmalonic acidemia with homocystinuria, type cblD is caused by changes (mutations) in the MMADHC gene and is inherited in an autosomal recessive manner. There is no cure for the condition. Treatments are focused on alleviating some of the associated symptoms and may include various medications and/or supplements.
Last updated: 11/9/2015

Disease Ontology
:12
A methylmalonic aciduria that is characterized by combined homocystinuria and methylmalonic aciduria and deficiency of MCM and MS activities.